Centering And Horizontal Width; Reinstall Cone Shield; Analog Card Adjustments - IBM 3278 Series Maintenance Information

5.1.3 Centering and Horizontal Width. Turn the
centering rings (see Figure 5-2) to center the hori-
zontal trace, both vertically and horizontally, on
line 1 of the alignment mask. The width (length of the
horizontal trace) should be 266.7 mm (10.5 inches)
as indicated by line 2 on the alignment mask. It may
be necessary to adjust the width potentiometer, width
(80), on the analog card (see Figure 4-6) together with
the centering rings.
5.1.4 Reinstall Cone Shield. When the yoke al ign-
ment, centering, and width adjustments are correct,
remove the jumpers from the analog card test points
and replace the cone shield by reversing the pro-
cedure in paragraph 5.1.1.
5.2 Analog Card Adjustments
There are five potentiometers (seven for Model 5) on
the analog card (see Figure 4-6) which may need ad-
justment when the analog card is swapped, or at other
times. Check the conditions described in the first
paragraph of this chapter before continuing.
I
Note: The NormalfTest switch must be in the
Test position.
1. See paragraph 5.1.3 for a description of the width
potentiometer.
2 Install a jumper between pins E02 G04 and E02
J08 (D) or F2G12 to F2J08 (M).
3. Adjust the top margin potentiometer so the top
trace of the first character line is centered on
line 3 on the alignment mask for the appropriate
model.
4. Adjust the character height potentiometer so the
bottom trace of the last character line is near the
line on the alignment mask for this model of the
3278.
5. Remove the jumper installed in step 2, and adjust
the row space potentiometer to obtain the total
vertical height of 101.6 mm (4 inches) for a
Modell, or 203.2 mm (8 inches) for all other
models (line 7).
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